Electronic component joining method and joined structure

Abstract

The present disclosure relates to an electronic component joining method and a joined structure. A solder layer made of a gold-tin alloy including 20 mass % or greater of tin is formed on a light-emitting element side, and a layer including gold as a main component is formed, as a joining layer for joining to the solder layer, on a submount side. The solder layer and the joining layer are heated at a temperature below the melting point of the gold-tin alloy of the solder layer to join the light-emitting element and the submount.

The invention claimed is: 
     
       1. An electronic component joining method of joining a side of an electronic component comprising an electrode and a side of a mount target object comprising a mounting surface, the electronic component joining method comprising:
 a layer forming step of forming a solder layer made of a gold-tin alloy comprising 20 mass % or greater of tin above the electrode of the electronic component, and forming a joining layer comprising gold as a main component above the mounting surface of the mount target object; and 
 a joining step of heating the solder layer and the joining layer at a temperature lower than a melting point of the gold-tin alloy, and joining the solder layer and the joining layer, 
 wherein 
 in the layer forming step, a first cohesion layer is formed on-above the electrode, and the solder layer is formed above a surface of the first cohesion layer. 
 
     
     
       2. The electronic component joining method according to  claim 1 , wherein
 in the layer forming step, a second cohesion layer comprising gold as a main component is formed above the first cohesion layer with a diffusion prevention layer comprising a platinum group element as a main component disposed between the first cohesion layer and the second cohesion layer. 
 
     
     
       3. The electronic component joining method according to  claim 1 , wherein
 the electronic component comprises a light-emitting element. 
 
     
     
       4. The electronic component joining method according to  claim 1 , wherein
 the electronic component comprises at least two electrodes on a surface of the electronic component facing the mounting surface of the mount target object. 
 
     
     
       5. The electronic component joining method according to  claim 1 , wherein
 in the layer forming step, an antioxidant layer comprising gold as a main component is further formed on a surface of the solder layer. 
 
     
     
       6. The electronic component joining method according to  claim 1 , wherein
 in the layer forming step, an antioxidant layer comprising gold as a main component is further formed on a surface of the solder layer, and the electronic component comprises at least two electrodes on a surface of the electronic component facing the mounting surface of the mount target object. 
 
     
     
       7. The electronic component joining method according to  claim 1 , wherein
 in the layer forming step, an antioxidant layer comprising gold as a main component is further formed on a surface of the solder layer, and in the layer forming step, a second cohesion layer comprising gold as a main component is formed above the first cohesion layer with a diffusion prevention layer comprising a platinum group element as a main component disposed between the first cohesion layer and the second cohesion layer. 
 
     
     
       8. The electronic component joining method according to  claim 1 , wherein
 in the layer forming step, a second cohesion layer comprising gold as a main component is formed above the first cohesion layer with a diffusion prevention layer comprising a platinum group element as a main component disposed between the first cohesion layer and the second cohesion layer, and the electronic component comprises at least two electrodes on a surface of the electronic component facing the mounting surface of the mount target object. 
 
     
     
       9. The electronic component joining method according to  claim 1 , wherein
 the electronic component comprises a light-emitting element, and the electronic component comprises at least two electrodes on a surface of the electronic component facing the mounting surface of the mount target object. 
 
     
     
       10. A joined structure having an electronic component comprising an electrode, and a mount target object comprising a mounting surface, the joined structure comprising:
 a solder layer made of a gold-tin alloy comprising 20 mass % or greater of tin, the solder layer located above the electrode of the electronic component; 
 a joining layer comprising gold as a main component, the joining layer located below the mounting surface of the mount target object; 
 an intermediate layer made of a gold-tin alloy with a lower melting point than a melting point of the solder layer, the intermediate layer being located between the solder layer and the joining layer; and 
 a cohesion layer comprising gold as a main component, the cohesion layer being located between the electrode and the solder layer. 
 
     
     
       11. The joined structure for the electronic component according to  claim 10 , wherein
 the solder layer is a gold-tin alloy comprising 20 mass % or greater and 30 mass % or less of tin. 
 
     
     
       12. The joined structure for the electronic component according to  claim 10 , wherein
 the solder layer is a gold-tin alloy comprising 20 mass % or greater and 30 mass % or less of tin, and the electronic component comprises at least two electrodes on a surface facing the mounting surface of the mount target object. 
 
     
     
       13. The joined structure for the electronic component according to  claim 10 , wherein
 the electronic component comprises at least two electrodes on a surface facing the mounting surface of the mount target object. 
 
     
     
       14. A joined structure having an electronic component comprising a first electrode and a second electrode, and a mount target object comprising a mounting surface, the joined structure comprising:
 a solder layer made of a gold-tin alloy comprising 20 mass % or greater of tin, the solder layer located above the electrode of the electronic component; 
 a joining layer comprising gold as a main component, the joining layer located below the mounting surface of the mount target object; and 
 an intermediate layer made of a gold-tin alloy with a lower melting point than a melting point of the solder layer, the intermediate layer being located between the solder layer and the joining layer, 
 wherein 
 the electronic component comprises the first and the second electrodes on a surface facing the mounting surface of the mount target object.